Building and Installing

Building this module requires that the user have installed the GLPK 4.18 or later, and GMP libraries. The module builds and appears to work on my simple test files in Python 2.4 and 2.5. Earlier versions of Python may not work. I have developed this on both OS X and Linux. I do not know if it will work on Windows.

Here are the brief instructions for installing.

  • Build the module using make. (Pay attention to warnings!)

  • Run make test to execute the test suite. You want the last line of output to be Tests succeeded!

  • Build the module using make install to install the module in your Python build’s site-packages directory. On a typical system, you will need to run this as the superuser (probably sudo make install).

In the ideal case (that is, you have GLPK and GMP libraries, headers, executables and the like installed in default search paths), this will just work.

Troubleshooting

A few details just in case things don’t go that easily:

How PyGLPK builds depends on which version of GLPK is installed. GLPK is an evolving library, and some functionality has been added only since older versions.

  • Perhaps you don’t have GLPK or GMP installed, or not the development versions with the headers.

  • Perhaps your INCLUDE_PATH, LIBRARY_PATH, or LD_LIBRARY_PATH paths are not set correctly.

  • Perhaps you have multiple versions of GLPK on your system in different locations, and it is confusing the system during building. E.g., it may build with one version, and then try to run the program with another.

  • Perhaps the GLPK library was installed incorrectly. For example, on my Ubuntu box, I cannot build anything with the GLPK installed by my Debian package manager, not even a simple main { LPX*lp=lpx_create_prob(); lpx_delete_prog(lp); }, owing to a faulty compile of the libraries.

If You’re Having Trouble Building

Below are some suggestions to try or avenues to pursue if you’re having trouble building. This is not an exhaustive list, just “the most likely suspects.”

  • The build process assumes that the default Python (i.e., the Python you would get if you tried executing python within sh) is the one for which you want to build glpk. If this is untrue, modify the Makefile file to change the assignment PYTHON:=python to something like PYTHON:=/path/to/other/python.

  • As described earlier, perhaps your environment variable paths are not set correctly. Relevant paths are INCLUDE_PATH, LIBRARY_PATH, LD_LIBRARY_PATH (yeah, I know).

  • Perhaps you do not actually have a glpk.h file in the include directories. This may be because you have a binary non-developer installation of GLPK.

  • Perhaps the setup.py script, in its attempt to do something reasonably clever, drew the wrong conclusions about where appropriate libraries and headers may be located, or the version of GLPK. (This may happen in certain situations where there are multiple builds of GLPK floating around with different versions, or your binaries are stored in strange locations.) Within setup.py is a small section beginning with USERS DO CUSTOM INSTRUCTIONS HERE where you can override its “cleverness” by manually defining the library name, location of appropriate library and include search directories, and other traits.

  • Multiple versions of GLPK as described earlier. This may be addressed through editing the setup.py

  • Faulty installation of GLPK.

If You’re Having Trouble Testing

Once you have built the module successfully and there is a glpk.so symbolic link defined to the shared library, you should run the principle test suite through make test.

If you’re running the test suite through make test and it throws some sort of exception, what the problem is depends on what type of error you see.

ImportError: No module named glpk

Ensure that the module actually built.

ImportError: (stuff) Symbol not found

Most likely, it cannot find a required library. Run ldd glpk.so (on Linux) or otool -L glpk.so (on OS X) to see which libraries it cannot find. Use this information to ensure that you environment variable LD_LIBRARY_PATH points to directories containing appropriate libraries. (Note that merely finding all libraries is not necessarily sufficient in the case where there are multiple GLPK libraries floating around. Ensure you’re not building with one, but running with the other.)

AssertionError (or other error)

The good news is that the module appears to load and run and it’s throwing normal Python exceptions. The bad news is one of my tests failed. This should not happen, but if it does, send me a bug report.</dd>

If You’re Having Trouble Installing

If it says permission denied when running make install, perhaps you need to run the command as the superuser, e.g., sudo make install.

Uninstalling

Like many Python modules, PyGLPK builds itself with the aid of Python’s included distutils module. As of the time of this writing, distutils does not support uninstallation. I am not comfortable with writing my own solution. Given that this is a potentially destructive option, there may be unintended, unfortunate consequences on some person’s configuration I did not anticipate. However, one may still uninstall PyGLPK by importing the glpk module, and checking the glpk.__file__ attribute. This will tell you where the module file is stored. Then, you can go to that directory and remove the module file, and the associated egg-info file, and rid yourself of PyGLPK.